Question: Solve for $x$ and $y$ using substitution. ${6x-4y = -8}$ ${x = -2y-4}$
Answer: Since $x$ has already been solved for, substitute $-2y-4$ for $x$ in the first equation. ${6}{(-2y-4)}{- 4y = -8}$ Simplify and solve for $y$ $-12y-24 - 4y = -8$ $-16y-24 = -8$ $-16y-24{+24} = -8{+24}$ $-16y = 16$ $\dfrac{-16y}{{-16}} = \dfrac{16}{{-16}}$ ${y = -1}$ Now that you know ${y = -1}$ , plug it back into $\thinspace {x = -2y-4}\thinspace$ to find $x$ ${x = -2}{(-1)}{ - 4}$ $x = 2 - 4$ ${x = -2}$ You can also plug ${y = -1}$ into $\thinspace {6x-4y = -8}\thinspace$ and get the same answer for $x$ : ${6x - 4}{(-1)}{= -8}$ ${x = -2}$